.bt1{
    width: auto;
    height: 50px;
    padding: 2px;
    border: black;
    margin-left: 20px;
    margin-top: 30px;
    background-color: yellow;
    color: red;
    font-style: normal;
    font-size: 18px;
    font-family: 微软雅黑 Verdana Arial sans-serif;
    align-content: center;
}
.bt2{
    width: auto;
    height: 50px;
    padding: 2px;
    border: black;
    margin-left: 20px;
    margin-top: 30px;
    background-color: blue;
    color: red;
    font-style: normal;
    font-size: 18px;
    font-family: 微软雅黑 Verdana Arial sans-serif;
    align-content: center;
}